Arrangement for supporting a work piece on the back center of a machine-tool



J. L; JEANNERET 2,874,600, UPPORTING A WORK HE 2 Sheets-Sheet 1 Feb. 24, 1959 ARRANGEMENT FOR S PIECE ON T BACK CENTER OF A MACHINE-TOOL Filed March 22, 1956 n a u 1 fIllIlfV/AWN \w w m W am" w M M M M Q K Wm EM. Q

Feb. 24, 1959 J. L. JEANNERET 2,874,600

ARRANGEMENT FOR SUPPORTING A WORK PIECE on THE v BACK CENTER OF A MACHINE-TOOL Filed March 22, 1956 2 Sheets-Sheet 2 m t Z A l 5 w; a M H: M I -6 Z M o w fi r .n. 4 xm 2 W T T l T\/ 5 .alllll FL.

ikliirl L will-Ill 2,874,600 Patented-Feb. 24, 1959 United States Patent Ofiice ARRANGEMENT FOR SUPPORTING A WORK .PIECE ON THE BACK CENTER OF A MA- CHINE-TOOL Jules Louis Jeanneret, Niort, France Application March 22 1956, Serial No. 573,223

Claims priority, application France April 14, 1955 is Claims. 01. 82-31) g My invention has for its object an arrangement for the rapid clamping of a piece of work on the back center ota lathe or the like machine-tool. tional' machine-tools, the operator can act only on a hand-wheel for the progression of the sheath or sleeve carrying the back center of the movable tailstock, I have Whereas in convenaction of a handle 8 mounted on said spindle. The overprovided in accordance with my invention an auxiliary arrangement which allows clamping the piece of work in an easy and speedy manner. This arrangement is con-.

stituted by a plunger fitted inside a casing rigid with the movable tailstock and adapted to make the screw conhanging of the eccentric member 11 is reduced to the utmost through such a mounting in a roller or ball bearing 12. t

It is apparent that this rotation of the eccentric member allowsa shifting of the plunger 17 between its non-clamping position illustrated in Fig. 4 and its clamping position illustrated in Fig. 3 as provided through the transverse movement imparted to the roller 12. It will be remarked that the plunger 17 islocked in its clamped position of Fig. 3 because the line connecting the center of the roller 12 with the center of the eccentric member 11 lies then slightly beyond the longitudinal axis 13 of the movable tailstock; On the otherhand, the eccentric member carries on its lower surface an arcuate groove 15 arranged coaxiallywith the axis of said member, said trolling the dead center progress longitudinally in its clamping direction, the plunger being controlled by a roller or the like member acting in parallelism with the axis of the dead center on a point of the plunger adjacent saidaxis under the control of a hand-operable eccentric member rotating round an axis perpendicular to the axis of the dead center.

According to an auxiliary feature of my invention, I providermeans for holding fast either the conventional hand-wheel when operating the high-speed clamping arrangement according to my invention or the latter when the conventional hand-wheel is being used.

I 'have illustrated by way of example in the accompanying drawings a preferred embodiment of the arrangement according to any invention as applied to a slide lathe. In said drawings:

Fig. l is a diagrammatic elevational view of the lathe incorporating my improved arrangement, said lathe being shown as a whole.

Fig. 2 is a longitudinal .verticalcross-section of the movable tailstock, the piece of work being shown: as held I by the high speed clamping arrangement.

Fig. 3 is a horizontalrpartialcross-section, through line 3-3 of Fig. 2, of the high speed clamping members, i. e. of the parts of the casing andof the plunger-associated with the eccentric roller, shown in plan view.

groove being engaged by a stud 14 rigid with the casing 1 or with a partrigidly secured to, the latter. The abutment of one end of saidgroove against the stationary stud 14 defines the maximum amplitude of shifting of the eccentric member beyond the point of maximum Fig. 4 is a view similar to Fig. 3, the plunger being released so as to allow the piece of work to be removed.

Fig. 5 is an elevational view similar to Fig. 4 except for the fact that, the clamping arrangement being locked, the movable tailstock .is ready-for operation for instance for boring a hole through the sole operation of the handwheel.

Turning to the lathe illust'rated by way ofexample in 6 Fig. l, the sleeve 3 of the movable tailstock 2 is adapted to progress in the direction ot the arrow 4 for clamping the piece of work 5 between the dead center 7 of the movable tailstock and the center. 6 of the stationary headstock. This progression is controlled normally by the usual 'hand wheel '10 and, to allow a rapid clamping without any substantial.v straining of the operator, there is provided as disclosed hereinabove an auxiliary arrangement illustrated diagrammaticallyin Fig. 1 through its casing l secu'red to the rear. of the movable'tailstock 2.

a perforation 21 (Fig. 5).

over- 1a ,short ,dist ar1 ce may thus be obtained whatever maly be the location lot the sleeve 3 obtained previously through operation of the hand-wheel 10. l

wedging on the longitudinal axis 13 as illustrated in Fig. 3.

Comparison between Figs. 3 and 4 allows ascertaining that a comparatively small shifting of the plunger under .theaction of the eccentric member. is sufficient for clamping the piece of work through the shifting thus imparted to the dead center 7 or the movable tailstock and reversely for releasing the dead center when ver the piece of work is being changed. V t

The plunger 17 acts on the system driving the back center 7 through the agency of the spring 16 and of the stop ring 28 rigid in its turn with the screw 9 engaging the sleeve 3; This shiftingof the 'dead center inside the movable tailstock under the. action of the handle 8 and of: the plunger 17 is thus independent of the shifting provided by the hand WheeI 10 the rotation of which pro duces mechanically that of the screw 9 which acts directly on the sleeve 3.

The'spring'16 inserted between the auxiliary arrangement and the center 7 makes up for the unavoidable justing at first the location of the sleeve 3 in a longitudinal direction and in order to prevent any misadjustment' o' f the dead center carried by the sleeve during the subsequent high speed clamping, the hand-wheel 10 is held fast longitudinally ,as-provided through the screwingfof "the screw 19 with aview to making the handwheel jrigid with the" washer 20..carrying an eccentric longitudinal 'rod 21 serving as aguide for the sliding of the system constituted by the hand-wheel 10 and the screw 9 inside the casing provided for this purpose with The high speed clamping Reversely, when it is desired to use the hand-wheel 10 alone without resorting to the highspeedclamping arrangement, the latter may be held fast after it has been returned into its inoperative position (Figs. 3 and 5) by screwing the screw 25:;(Fig. 2) through an opening of the casing 1 so as to make it engage a conical depression 2 6 provided in the' outer 5 wall of the spindle carrying the eccentric member.

The screw 19 is then released so that his possible' henceforward to use the hand-wheel in the same manner as on a conventional tailstock, for instance when drilling. This is allowed byreason of the collarj27 rigid with the shank of the control screw 9 'engagingthefrontf surface of the "casing 1*a's shown in-"Fig'QS was to 'de fine in anaccurate manner thelocation' of the control screw 9 with reference tothe 'ni'ovable' tailsto'ckr The shifting of the sleeve is 'then 'op'er'ated solely 'thro'ughithe rotation of the hand-wheel.

Of course, for executing a highspeed?clamping through operationfof the handle 8 it jis' necessary 'fto"previously" unscrew the'screw so as to'releaseihe eccentric'mem? her. The operation continues thenafter in'th'e manner disclosed hereinabove, the plunger 17 sliding so as'to' shift forwardly the washer 20*which is rigid with the screw and with-the hand-wheel.

What I claim is: t l. A double control'system' forj the 'positioning of' the back center in the tailstock of a-machine-tool, comprising a casing rigid with the outer end of 'the tailstock, a. sleeve slidin'gly, 'nonrotatably' and coaxially fitted inside side-the tailstock and casing system, ,earrying' thefback center and the outer end of'whichis-tapped,"a"shank extending axially'o'f the tailstock andc'asing syst'em and a section of which for ms a' control screwjengagingflthe" outer tapped'endof thefsleeve, a handwheel coaxially rigid with'said shank and adapted to be rotated" with reference to the casing to control the position ofjthe" sleeve in'side'the tailstock, a stop rigid with the shank at'a point outside its screw=section, a plunger surrounding 40 a shank section between-saidistop andihe handwheel and adapted to slide thereon inside the casing and; when shifted'inwardly, the urge pnsitively' and bodily inwardly the stop, the shank, thesleeve and the'backeenter, said plunger being provided with a rectilinear groove-perpendicular to'the axis ofithe shank,a spindlere'volubly carried bythe casing andthe axis of whiclfpaSsthroughf the plunger orthogonally to the axis of the shank'jand to the directionof saidgroove, a member rigid with.

stop limiting said'fu'rther progression of the projebtibnf to a slight amount andhand-operable nie a n's" rigid with;

the spindle on the outside of the casing forcontrol of the rotary movement of- ,the spindleandime'mber rigid therewith.- V t 2'. A double control system for the positioning" of the? back center in the tailstockof a machine-tool, comprisk ing a casing-rigid with the outer end of thetailst'ock, a

sleeve :slidin'gly, non rotatably and coaxially fitted in-, H

side the tailstockand casing system, carrying the back center and the] outer end of which is tapped, ashank' extending" axially of the tailstock and casing system" and I a section of which' forms a control screWJengagingQ the outer tapped end of the sleeve, a handwheelfcoaxially rigid with said shank and adapted t'o'be'rotated' with referenceto the casing to control the position of the sleeveinside the tailstock, a stop rigid with 'the 'sh'ank at a point outside its scre'wsectionand cooperating with" with reference to the casing, a'plunger surrounding a shank section between said stop and the handwheel and adapted to slide thereon inside the casing and, when shifted inwardly, tourge positively and bodily inwardly the stop, the shank, the sleeve and the back center, said plunger being provided with a rectilinear groove perpendicular to the axis of the shank, a spindle revolubly carried by the casing and the axis of which passes through the plunger orthogonally to the axis of the shank and to the direction of said groove, a member rigid with the said spindle at the end of the latter facing the plunger, a roller revolubly carried eccentrically by said member, engaging the groove in the plunger and adapted to progress in said groove upon rotation'of-the spindle to make said plunger progress inwardly as said roller progresses between an end of said groove and a point of the said groove aligned longitudinally of-the shank with a point of the axis of the spindle, further progression of the roller beyond said point releasing .the plunger, a stop limiting said'further progression of'th'e roller to a slight amount and'hand-operable' means rigid with the spindle on the outside of the casing for control'of the rotary movement of the spindle and member rigid therewith.

3. A double control system for the positioning ofthe back center in the tailstock of a machine-tool, comprising a casing rigid with the outer end of the tailstock, a sleeve slidingly, non rotatably and coaxially'fitted insidethe' tailstock and easing system, carrying the back center and the'outer end'of whichis tapped, ashank extending axiallypf thgtailstock and casing system-and'a section of which fornrs' a control screw engagingthe outer tapped end of the sleeve, a handwheel coaxially'rigid with said shank and adapted to be rotated with reference to the ca'singto control the. position'of the'sleeve inside the tailstock,"a.1stop rigid "with the'shank at a point outside its'screw' section; a plunger surrounding a sha'nk'section between said stop and the handwheel and adapted to slide thereon inside the casing and, when shifted inwardly, to urge positively and bodily inwardly the stop, the shank, the sleeve'and the back center, said plunger being provided witharectilinear groove perpendicular to the axis of the shank, a spindle revolubly carried by the'c'asing' and the axis of whichpasses'throughthe plunger orthogmany to' the axis of the shank and to the direction vof said groove; a cam rigid with the said spindle at the end of the latter facing the plunger,.engaging the'groove' in the'plun'ger-and adapted to progress in said groove upon rotation of'the spindle to'make said plunger progress inwardly as said cam progresses between an end of said groove and'a point, of the said groovealigned longitudi nallyof the shank with'a point of the axisof the spindle, further progressionof the cam beyond said point releasing the p'lunger, a stop limiting said further vprogression of-the cain to a slight amount andhand-operable means rigid'with"the-spindle on the'outside' of the casingvfor control of the rotary movementof the spindle'and cam rigid therewith. V

4. A double control system for the positioning of the back center in the tailstock of a machine-tool, comprising a casiti'g-rig'id with'the outer endof theftailstock, a sleeve slidin'gly, non rotatably and coaxiallyfitted. inside the tailstock and easing system, carrying the back center and theouter end of which is tapped, a shank extending axiallyhof the tailstockhnd'"casing system and a section I of which-forms acontrol-screw engaging the outer tapped end jof the; sleeve, ahandwheel coaxially rigid with said shank and adapted to be rotated'with reference tovthe casing to"c'0ntrol' the position" of th'e sle'eve' inside the tailstock, a stop rigid'with'the shank: at a point outside its's'crewsection; a'plunger surrounding a'cshank section between sa'id stop andthe handwheel; and adapted to slide thereon inside the casing and, when shifted inwardly, to urge positively and bodily inwardly th'e stop, the shank, the sleeve and the back center,'said' plunger being proaisnieoo" vided'with a rectilinear groove perpendicular toth'el'axis of the shank, a spindle the axis of which passes through; the plunger orthogonally tothe-axis of the shank'andto the direction of said groove, roller bearings rigid with the casing and revolubly carrying isaid spindle, a member rigidwith the said spindle at the end of the latter facing the plunger, a projection carried eccentrically by said member, engaging the groove in the plunger and adapted to. progress in said groove upon rotation of the spindle to make said plunger progress inwardly as said projection progresses between an end of said groove and a point of the said groove aligned longitudinally of the shank with a point of the axis of the spindle, further progression of the projection beyond said point releasing the plunger, a stop limiting said further progression of the projection to a slight amount and a handle controlling said spindle and radially rigid therewith.

5. A double control system for the positioning of the back center in the tailstock of a machine-tool, comprising a casing rigid with the outer end of the tailstock, a sleeve slidingly, non rotatably and coaxially fitted inside the tailstock and casing system, carrying the back center and the outer end of which is tapped, a shank extending axially of the tailstock and easing system and a section of which forms a control screw engaging the outer tapped end of the sleeve, a handwheel coaxially rigid with said shank and adapted to be rotated with reference to the casing to control the position of the sleeve inside the tailstock, a stop rigid with the shank at a point outside its screw section, a plunger surrounding a shank section between said stop and the handwheel, a damping spring fitted between the plunger and the stop to transmit the thrust of the plunger when shifted inwardly to said stop and thereby urge positively and bodily inwardly the shank, the sleeve and the back center, saidplunger being provided with a rectilinear groove perpendicular to the axis of the shank, a spindle revolubly carried by the casing and the axis of which passes throughthe plunger orthogonally to the axis of the shank and to the direction of said groove, a member rigid with the said spindle at the end of the latter facing the plunger, a projection carried eccentrically by said member, engaging the groove in the plunger and adapted to progress in said groove upon rotation of the spindle to make said plunger progress inwardly as said projection progresses between an end of said groove and a point of the said groove aligned longitudinally of the shank with a point of the axis of the spindle, further progression of the projection beyond said point releasing the plunger, a stop limiting said further progression of the projection to aslight amount and hand-operable means rigid with the spindle on the outside of the casing for control of the rotary movement of the spindle and member rigid therewith.

6. A double control system for the positioning of the back center in the tailstock of a machine-tool, comprising a casing rigid with the outer end of the tailstock, a sleeve slidingly, non rotatably and coaxially fitted inside the tailstock and casing system, carrying the back center and the outer end of which is tapped, a shank extending axially of the tailstock and easing system and a section of which forms a control screw engaging the outer tapped end of the sleeve, a handwheel coaxially rigid with said shank and adapted to be rotated with reference to the casing to control the position of the sleeve inside the tailstock, a stop rigid with the shank at a point outside its screw section, a plunger surrounding a shank section between said stop and the handwheel and adapted to slide thereon inside the casing and, when shifted inwardly, to urge positively and bodily inwardly the stop,

the shank, the sleeve and the back center, said plunger being provided with a rectilinear groove perpendicular to the axis of the shank, a spindle revolubly carried by the casing and the axis of which passes through the plunger orthogonally to the' axis of the shank and to the direction of said groove, means for locking said spindle at the end of the latter facing the plunger, a projection carried eccentrically by said member, engaging the grove in the plunger and adapted to progress in said groove upon.rotation of the spindle to make said plunger progress inwardly as said projection progresses between an end of said groove and a point of the said groove aligned longitudinally of the shank with a point of the axis of the spindle, further progression of the projection beyond said point releasing the plunger, a stop limiting said further progression of the projection to a slight amount and hand-operable means rigid with the spindle on the outside of the casing for control of the rotary movement of the spindle and member rigid therewith.

7. A double control system for the positioning of the back center in the tailstock of a machine-tool, comprising a casing rigid with the outer end of the tailstock, a sleeve slidingly, non rotatably and coaxially fitted inside the tailstock and casing system, carrying the back center and the outer end of which is tapped, a shank extending axially of the tailstock and casing system and a section of which forms a control screw engaging the outer tapped end of the sleeve, a handwheel coaxially rigid with said shank and adapted to be rotated with reference to the casing to control the position of the sleeve inside the tailstock, a disc revolubly carried by the shank, guiding means for said disc allowing a longitudinal movement thereof with reference to the casing, releasable means rigidly interconnecting the handwheel with said disc to prevent angular shifting of the handwheel, a stop rigid with the shank at a point outside its screw section, a

plunger surrounding a shank section between said stop and the handwheel and adapted to slide thereon inside the casing and, when shifted inwardly, to urge positively and bodily inwardly the stop, the shank, the sleeve and the back center, said plunger being provided with a rectilinear groove perpendicular to the axis of the shank, a spindle revolubly carried by the casing and the axis of which passes through the plunger orthogonally to the axis of the shank and to the direction of said groove, a member rigid with the said spindle at the end of the latter facing the plunger, a projection carried eccentrical- 1y by said member, engaging the groove in the plunger and adapted to progress in said groove upon rotation of the spindle to make said plunger progress inwardly as said projection progresses between an end of said groove and a point of the said groove aligned longitudinally of the shank with a point of the axis of the spindle, further progression of the projection beyond said point releasing theplunger, a stop limiting said further progression of the projection to a slight amount and hand-operable means rigid with the spindle on the outside of the casing for control of the rotary movement of the spindle and member rigid therewith.

8. A positioning and locking system for a longitudinally movable shaft, comprising a plunger shiftable over said shaft and adapted to urge the latter forwardly into a predetermined position, said plunger being provided with a rectilinear groove perpendicular to the axis of the shaft, a spindle revolubly carried by the casing and the axis of which passes through the plunger orthogonally to the axis of the shaft and to the direction of said groove, a member rigid with the said spindle at the end of the latter facing the plunger, a projection carried eccentrically by said member, engaging the groove in the plunger and adapted to progress in said groove upon rotation of the spindle to make said plunger progress inwardlyas said projection progresses between an end of said groove and a point of the said groove aligned longitudinally of the shaft with a point of the axis of the spindle, further progression of the projection beyond said point releasing the plunger, a stop limiting said further progression of the projection to a slight amount and hand-operable 7-1 for: control ,of. the rotary; movement 7 of ;the spindle 9.116; 1,290,896 member rigid therewith. 1,373,158;

1 1" References Cited in the file, ofnthisupatent v UNITEDJSTATESIPATENTSl 1 v 5 722;677' Cripph et-'al.' Men? 17,1990? 1,004,563

Mar. 29, 1921v Townsend Ju1y'15;u1924-' FOREIGN PATENTS: Fiance Mar. 13,1952 

